JP2636431B2 - Error correction device and error correction method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error correction apparatus and an error correction method used for transmitting or recording image information.

2. Description of the Related Art Since image information is generally divided into specific blocks and transmitted or recorded, data may be lost in block units due to a transmission path error or the like. On the other hand, in the past, the block was modified by replacing it with a block one page before (one page represents one field or a plurality of fields) of the block. Since image information has a very large correlation between pages, it was possible to efficiently reproduce a block that has been lost by such a modification.

Problems to be Solved by the Invention However, in the above-described configuration, when the scene is changed from that of the previous page, the correlation between the pages is reduced, so that a large distortion may be caused by the modification. In addition, if the number of lost blocks increases by repeating transmission or recording, blocks that are further modified using the modified blocks are generated, and image quality is deteriorated in images with large motions.

An object of the present invention is to solve the problem of such a conventional error correction device.

Means for Solving the Problems The present invention provides a method for transmitting or recording digital moving image information in which one page is composed of one field or a plurality of fields, data is divided into blocks in each page, and blocks are transmitted. When a block is lost due to a transmission path error or the like, the block data is replaced by one of the data of the block at the same position one page before and the data of the block at the same position one page after. And a correction information recording means for recording information indicating which page of the block has been replaced by the block replaced by the previous block replacement means.

Operation With the above-described configuration, there is a possibility that the data of the block currently lost by the block modified in the past can be completely reproduced, and the probability that the block at the same position will be lost for two consecutive pages is extremely low. For this reason, it is possible to minimize the deterioration of image quality due to repeated transmission and recording.

Examples Examples of the present invention will be described below.

FIG. 1 is a block diagram of an embodiment of the first invention of the present invention. In FIG. 1, 1 is a one-page delay portion, 2 is a modification judgment portion, 3 is a switch, and 4 is a one-page delay portion. The operation of the embodiment shown in FIG. 1 will be described below. The block that has been transmitted or recorded and input is first input to the one-page delay section 1. The block output from the one-page delay section 1 determines whether or not the block has been erased by the error correction or error detection result in the modification determination section 2. If the data has been erased, the block after one page input and the block before one page output from the one-page delay section 4 are compared to determine which of the data contents is closer. Then, the switch 3 selects the output of the one-page delay part 1 if it is not lost, and if it is lost, the modification judgment part 2
Select the block of the page selected by. Switch 3
Are output via the one-page delay section 4. Here, a method of determining whether to select the block one page before or the block one page behind in the modification determination part 2 will be described. In image information, spatially adjacent data has a very high correlation. Therefore, the data in a block adjacent to the lost block (for example, the block immediately before) is determined as to whether it is closer to the block one page before or one page after the adjacent block,
The information is used to determine the lost block. This makes it possible to select a block on a page that is highly correlated with the block that has been lost in most cases. As another method, data of a lost block is used. In general, a large number of data that are not erroneous actually exist in a lost block. Therefore, by comparing the data of the block before one page and the data of the block after one page with the data of the lost block and selecting a block in which a large number of close data exists, a block having a large correlation can be selected. According to the first aspect of the present invention, it is possible to perform correction using data of a block which is closer to one page before or after one page, so that image quality degradation can be minimized even when a scene changes between pages. Will be possible. Next, FIG. 2 is a block diagram of an embodiment of the second invention of the present invention. 5 is a one-page delay portion, 6 is a modification information detection portion, 7 is a modification judgment portion, 8 is a switch,
Reference numeral 9 denotes a modification information writing portion, and reference numeral 10 denotes a one-page delay portion.

The operation of the embodiment shown in FIG. 2 will be described below. The input block transmitted or recorded and reproduced is first input to the one-page delay section 5. The modification information detecting section 6 detects the modification information of the block after one page inputted and the modification information of the block of one page before outputted from the one-page delay section 10 and uses the data of the block currently being processed. It is detected whether or not the modification has been made in the past, and is input to the modification judging section 7. The block output from the one-page delay section 5 determines whether or not this block has been erased according to the result of error correction or error detection in the modification determination section 7. If it is not lost, the switch 8 selects the block as it is. When this block is determined to be lost, if a block modified by this block (a block one page before or one page after) exists in the past according to the information input from the modification information detection part 6, The switch 8 is controlled so as to select the modified block. If there is no block that has been modified in the past, it is determined which data of the block one page before or one page is closer, and the switch 8 selects the closer data. The block selected by the switch 8 in this way is the modification information writing portion 9
Is input to In the modification information writing section 9, if there is no block modified in the past and the modification has been performed, information indicating which page (before or after) the block has been modified is written as modification information. The output of the modification information writing section 9 is output via a one-page delay section 10. By replacing the data of the lost block with the data of the block modified in the past, the original data can be completely reproduced. This greatly reduces the probability that a block at the same position will be lost for two consecutive pages, so that it is possible to improve image quality degradation when transmission and recording are repeated. Further, in order to simplify the apparatus, it is possible to limit the modification to always rewrite the block in the block one page before. As a result, it is not necessary to detect the correlation between pages, and it is sufficient to always detect only the modification information after one page.

According to the first aspect of the present invention having the above-described configuration, it is possible to modify a block having a large correlation either one page before or one page later, so that the image quality is degraded even when the scene changes between pages. Does not occur. Therefore, it is possible to minimize the image quality deterioration due to the modification. Further, according to the second invention, there is a possibility that the data of the block which has been lost by the block modified in the past can be completely reproduced, and the probability that the block at the same position will be lost for two consecutive pages is extremely low. For this reason, it is possible to prevent the image quality from deteriorating by repeating transmission and recording.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the first invention, and FIG.
FIG. 4 is a block diagram of an embodiment of the present invention. 1 ... 1 page delay part, 2 ... Modification judgment part, 3 ...
Switch, 6: Modification information detection portion, 7: Modification information writing portion.

Claims (5)

(57) [Claims] When digital video information is composed of one field or a plurality of fields in one page, and data is divided into blocks in each page and transmitted or recorded for each block, a transmission path error or the like may occur. Block replacement means for replacing the data of the block with one of the data of the block at the same position one page before and the data of the block at the same position one page after when the block is lost; A correction information recording means for recording information indicating which page block has been replaced by the block replaced by the means. 2. The digital moving picture information, when one page is composed of one field or a plurality of fields, and data is divided into blocks in each page and transmitted or recorded for each block, a transmission path error or the like causes. When a block is lost, the data of that block is replaced with either the data of the block at the same position one page before and the data of the block at the same position one page after, and the replaced block An error correction method characterized by adding information indicating whether a page block has been replaced. 3. A block replacement means for detecting modification information of a block located at the same position one page before the block and modification information of a block located at the same position one page after the block. If there is a block replaced by a block that is currently lost, the first block replacement unit that replaces the block with that block, and if there is no block that has been replaced by a block that is currently lost in the past by the detection unit, 2. The error correcting apparatus according to claim 1, further comprising: a judging unit for judging which block is closer to the data, and a second block replacing unit for replacing a lost block with the block selected by the judging unit. . 4. The error correcting apparatus according to claim 3, wherein said judging means makes a judgment based on a correlation between pages of blocks adjacent to the lost block. 5. The error correction apparatus according to claim 3, wherein said judging means judges by estimating a correlation between pages by using data in a block regarded as lost.